This application claims priority from Japanese Patent Application No. 2006-274327, filed on Oct. 5, 2006, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
Apparatuses consistent with this invention relate to a reflection-type bandpass filter for use in ultra-wideband (UWB) wireless data communication.
2. Description of the Related Art
As technology of the related art, for example, the technology disclosed in the following references 1 through 12 is known.
Reference 1: Specification of U.S. Pat. No. 2,411,555
Reference 2: Japanese Unexamined Patent Application No. 56-64501
Reference 3: Japanese Unexamined Patent Application No. 9-172318
Reference 4: Japanese Unexamined Patent Application No. 9-232820
Reference 5: Japanese Unexamined Patent Application No. 10-65402
Reference 6: Japanese Unexamined Patent Application No. 10-242746
Reference 7: Japanese Unexamined Patent Application No. 2000-4108
Reference 8: Japanese Unexamined Patent Application No. 2000-101301
Reference 9: Japanese Unexamined Patent Application No. 2002-43810
Reference 10: K. W. Tan and S. Uysal, “Analysis and design of conductor-backed asymmetric coplanar wave-guide lines using conformal mapping techniques and their application to end-coupled filters,” IEICE Trans. Electron., vol. E82-C, no. 7, pp. 1098-1103, 1999.
Reference 11: A. V. Oppenheim and R. W. Schafer, “Discrete-time signal processing,” pp. 465-478, Prentice Hall, 1998.
Reference 12: G-B. Xiao, K. Yashiro, N. Guan, and S. Ohokawa, “An effective method for designing nonuniformly coupled transmission-line filters,” IEEE Trans. Microwave Theory Tech., vol. 49, pp. 1027-1031, June 2001.
However, some bandpass filters proposed in the related art do not satisfy the FCC specifications, due to manufacturing tolerances or other reasons.
Further, in a bandpass filter of the related art, surface waves arising from undesirable slot line modes are excited when the ground potentials on the two sides are different, and so the need arises to provide an air bridge between the grounds on the two sides, and the device becomes susceptible to external influences (see Reference 10).
Exemplary embodiments of this invention were devised in light of the above circumstances, and have, as an exemplary object, the provision of a high-performance UWB reflection-type bandpass filter which is not susceptible to external influences, and which satisfies FCC specifications.